Cue competition refers to the failure of subjects to respond to a predictive cue, due to that cue having been trained in the presence of a cue perceived to be a better predictor. For example, the presence of a previously established predictor of the outcome during training 'blocks' a second cue from gaining behavioral control when the two are trained in compound. As a result, subjects appear to ignore accurate predictors of critical events. This is of little consequence when the superior predictor is present, but results in errors in behavior (and judgement) if it is absent. Recent research has found that cue competition response deficits are due at least in part to a failure to express information that was encoded, rather than a failure to acquire the information. The Comparator Hypothesis of Response Generation appears to be a viable framework for understanding this last feature of cue competition effects. The proposed studies are intended to improve understanding of the variables that influence cue competition, the processes underlying it, and how it can be alleviated or even prevented. Most of the studies will use rats in Pavlovian situations. A) The PI will test the view that cues that are biologically relevant due to their inherent or acquired attributes are protected from cue competition. B) The Comparator Hypothesis predicts that posttraining associative deflation and inflation of other cues that were present during training of the CS (i.e., comparator stimuli) will influence responding to the CS. This was confirmed for deflation but not inflation. The PI will examine the basis of previous failures of comparator cue inflation to affect responding to the CS. C) The PI will determine if the comparator role of a stimulus is modulated by the context used for testing, as is simple Pavlovian excitation (i.e., 'renewal'). D) Although the existing literature suggests that a stimulus' Pavlovian excitatory and occasion setting properties are independent, the rules governing these two families of properties closely parallel one another. The PI will investigate whether a cue's occasion setting properties are subject to cue competition as are its Pavlovian excitatory properties. E) Knowledge of Pavlovian cue competition is based largely on studies using animal subjects. Toward generalizing these findings to more complex learning processes, the PI will examine some of the previously mentioned issues with human subjects in casual judgment tasks and purely Pavlovian situations.